Baystate Jeepers

ok so im going to be geting paid this friday (HURAYYY)
what is a good coldair intake for the 2.5L
also what is a good exhaust that wont sound like a fartcan on the 2.5L

Stock on both.

Intake; I bored a couple of 4" holes into the side of my stock air box. I run a replacement Fram paper element. I do have a new K&N that a friend gave me, but I would not buy one myself. The paper elements filter out fine dust better than the oiled cotton gauze, IMO. The synthetic filter media filters are supposed to be nice though.

Exhaust; I have run Magnaflow, Flowmaster, and even a Thrush. IMO, they're too loud and annoying. When my cat died last year, I replaced it (even though I no longer have emissions testing) and went with a direct replacement, quiet, muffler. I think it's a Walker. The four popper and 4.0L Wranglers share the same size exhaust system. That means the 2.5L has plenty of flow for power.

My recommendation: Mod your airbox, drop in a new filter, and if the exhaust isn't broke - leave it be. Drop your coin on suspension or other mods.

I'd look at JP Magazine's website... In general though, after reading their tech articles for some years, they basically will say there isn't much you can do to improve the 2.5L 4-cyl.

One thing I've heard of is to put a larger throttle body off an I6 on there, but I'm not sure what the results were... I know some of JP's articles show loss of power when they modded the stock configuration.

JW

2.5L's are nice, reliable engines. There are some performance upgrades that you can do without tearing into the engine with a new cam or overbore, or buying a super/turbo charger.

On my 2.5L, I removed the head and cleaned it up by hand. I also cleaned up the intake manifold and made sure the gaskets were port matched.
I run a 4.0L throttle body with a phenolic spacer. The intake was sized for the smaller 2.5L TB, so I bored and smoothed the hole out to match the 4.0L TB.
The stock ignition provides plenty of zap, but I do use Accel 8mm wires. I opened up the air box with 2 4" holes and removed the sound attenuator.

The engine was out of a '95 and IIRC, was spec'd the same as my '92 @ 123 HP. The XJ version was rated to 130 HP. With the mods I did, my butt dyno feels like I'm pushing about 135 to 140 HP, with about 150 ft-lbs of torque. Those numbers may actually be a little shy, as I did very well during the road trips to the trail head out in Moab with my 38's and 4.09 gears. We used the YJ for the last camping trip to the White Mountains towing about 1200 lbs of trailer with 3 adult and 1 child size people on board. I was able to maintain 70 mph easily (although I did drop to about 55-60 during steep climbs).


The best way to keep your 4 cylinder peppy, is to give it more mechanical advantage with new axle gears. When the time comes, I'll be dropping in a set of either 5.13's or 5.38's, depending on what is available for my front high pinion Dana 44.

A set of 4.88's in your rig would really make it zip.

hmm i think im going to go do that airbox thing and i think ill keep the exhaust stock, Thanks for the help

Hey Wesley,
I'm going to be picking up a 4.0L throttle body on the NEOW forum. To be honest, I already run one and also have three complete spare 2.5L TB's.
The guy wants $25.00 shipped. I can put you in touch or buy it and "sell" it to you when I see you.

Interested? Here's the thread: http://forum.neow.net/index.php?showtopic=95221

yeah ill pm u about it